Non-destructive inspection of structures involves thoroughly examining a structure without harming the structure or requiring significant disassembly of the structure. Non-destructive inspection is advantageous for many applications in which a thorough inspection of the exterior and/or interior of a structure is required. For example, non-destructive inspection is commonly utilized in the aircraft industry to inspect aircraft structures for any type of internal or external damage to the structure.
Among the structures that are routinely non-destructively inspected are composite structures. In this regard, composite structures are commonly used throughout industry because of their engineering qualities, design flexibility, and low weight. As such, it is frequently desirable to inspect composite structures to identify any flaws, such as cracks, voids, or porosity, which could adversely affect the performance of the composite structure.
Various types of sensors may be utilized to perform non-destructive inspection. One or more sensors may move over the structure to be examined, and receive data regarding the structure from which internal flaws can be identified. For example, a pulse-echo, thru-transmission, or shear wave sensor may be utilized to obtain ultrasonic data, such as thickness gauging, detection of laminar defects and porosity, and/or crack detection in the structure. Resonance, pulse echo, or mechanical impedance sensors may also be utilized to provide indications of voids or porosity, such as in adhesive bondlines of the structure. The data acquired by the sensors is typically processed by a processing element, and the processed data may be presented to a user via a display.
Accessibility to the features of the structure requiring inspection is one consideration in choosing a non-destructive inspection device. Access to the feature requiring inspection may be so limited that a manual inspection by a technician is not possible. An example of a structure with limited access is an internal joint of a wing structure. More specifically, the bondlines produced by close-out joints created when the last sections of the wing are attached exemplify the limited-access features of a structure.
Limited-access features of a structure, such as the close-out joints, are difficult to fully inspect using contemporary inspection devices. Accordingly, a need exists for a convenient and reliable non-destructive inspection device to inspect limited-access features of a structure.